Handle control for electrically driven lift trucks



y 14,1953 o; c. G. WENNBEIG ETAL- 2,645,297

HANDLE CONTROL FOR ELECTRICALLY DRIVEN LIFT TRUCKS Filed April 29. 1949I 5. Sheets-Sheet 1 amxs app ssca/vo OR BRA/ E a/v FIRST 51 5 0 0 rBRAKE air/= 5% I @hq Z JW HANDLE CONTROL FOR ELECTRICALLY DRivEN LIFTTRUCKS Filed April 29, 1949 July 14 1953 o. c. e. WENNBERG ETAL 3 Sheets-Sheet 3 Patented July 14, 1953 "oFFIce HANDLE CONTROL FoaELECTRJCAlILY v DRIVEN LIFTTRUCKS,

010v Carl Gustav Wennberg and vCurt Erik A Simon Wennberg, Karlstad,wede'n Application April 29, 1949, serial No. 90,362

In Sweden May 7, 1948 1 9 Claims. (01. 180-65),

- This invention relates to lifttrucks and more particularly toelectrically driven lift trucks of the type which is provided with anoperating lever or rod swingable within a certainangle, preferably in avertical plane, in one direction or the other. Usually such lever or rodis utilized for steering the truck in different driving directions.

The main object of the invention is to provide a suitable controlmechanism for lift trucks of the type referred to above. V r Afurtherobject of the invention is to provide acontrol mechanism forelectrically motor driven lift trucks, said control mechanism comprisinga blocking contrivance determining the various control positions of acontrol member or handle in dependence upon the positions of theoperating lever within the angle in which this lever can be adjusted.

A still further object is to provide means whereby the operating handleand the operating lever are adapted to cooperate so as to obtain areliable control of the driving means of the lift truck: 7

An object of the invention is also to provide a control mechanism forlift trucks in which braking of the driving means of the truck, drivingatdifferent speeds, and driving forward as; 7 well as backward may beeffected dependent upon the position of theoperating lever or rod withinvarious zones of the angle, within which it can be set.

A more particular object of the invention is to provide a controlmechanism for lift trucks. having an operating lever beinggenerallyswingable between two extreme positions, such as a verticalposition and a horizontal position. The operating lever may be adaptedto cooperate with the blocking contrivance and a contact membercontrolled thereby so as to take the extreme position or positionswithin a small angle next to the same when the contact device is set tokeep the motor cut off, while a braking device is preferably beingengaged to prevent the truck from rolling, the motor being thenstationary. These angular ranges of the operating lever may thusbe'designated as the braking zones. Adjacent these zones there may be azone within the swingsired. It is possible to make use of all of the ingranges of the operating lever, within which zones ofv speed for forwarddrive-and of all of them for backward drive. r

The invention consists in the features of construction, combinationofelements, and arrangements of parts as will be exemplified inthemechanism to be hereinafter described and the scope of theapplication. of which willbe indicated in the following claims.

In, the. drawings in which oneflembodiment of carrying the same,. saidparts. .including a cam and a braking device,

Figure 3a is a part sectional view on line 1IIa 11m in Fig. 31andillustrates a detail of the braking'device.

Figure 4 is a vrticn seamen view on a plane at right anglesto thesection shown in -Fig.- 3,

the upper portion of the operating lever being removed. I v v Figures5-9 are diagrammatic representations ofdifierent positions of theoperating handle of the contact device. I v

Figurelo is a coupling diagram illustrating, in a simplified way,,,theelectrical connections between the contact deviceand the driving motor.

Figure loa is an elevation of the contact member shownin Fig. 10 asseen" from the left in rigid. H

In the structure shown inthe drawings, the lift truck broadly comprisesa part adapted to receive the'load,.said part having two rearw ardlydirected legs I carried each by a wheel (or roller) 2, a frame iivarranged -in..frontg of said parts, an electricaljdriving motor unit 4comprising a carrying traction wheel5 and adapted to be turned in theframe 3 ing axis of the lift truck, and a storage battery 6 secured tothe frame 3. The steering axis may be determined byv a ball bearing 4abetween a rotatable steerin ring lband a stationary steeringring 40;secured .to the frame 3 as shown in Fig. 3, the steeringring 41) beingcarried by the wheel axle journals Ed by way of journal brackets Ad. 'Inaddition to the driving motor, the motor unit comprisesa transmissionbetween the motor and the carrying traction wheel 5 and controllingmeans for the driving motor and the transmisabout a vertical axis,.thesteersion. The latter is adapted to be thrown into service by electricalmeans, and is indicated in Fig. 3 as two belt transmissions b, 5c, 5d.and 50a, 50b, 580 respectively. Mounted in a bearing housing I on thefront portion of the driving motor unit A is an operating rod or lever8, in a manner such that the rod is permitted to be swung about ahorizontal axis of rotation 9, preferably from a vertical extremeposition (full lines in Fig. 1) into a horizontal extreme position(chain-dotted lines in Fig. l), or vice versa. The lift truck may besteered by means of the operating rod 8 in different driving directionsby the turning of the driving motor unit about the vertical steerin axisand, furthermore, the operating rod is used to control the driving motorand a braking device actuating the traction wheel 5. fhis driving motorcontrol and actuation of the brakes is effected by the swinging of theoperating rod 8 into different angular positions between said extremepositions, a contact device provided in the operating rod then permittedto be adjusted into various positions of control in. dependence on theposition of the operating rod within said angle. The driving motor isdis- =4 engaged and the brake engaged in the extreme positions, and nextto the extreme positions are the braking zones 0, 0' within which thebrake is also kept engaged. If the operating rod is swung down throughthe braking zone 0 from the vertical extreme position and continuesdownward, it passes over to an angular zone I, within which the lowerspeed may be thrown into service by means of the contact device, andupon a continued swinging movement the operating 1.

rod is brought into an angular zone II, where the higher speed may bethrown into service. Within this zone, the lower speed also may bethrown into service instead of the higher speed, if desired. After thatfollows an angular zone 1', within which only the lower speed can bethrown into service, and finally follows the braking range 0 adjacent tothe horizontal extreme position, wherein braking takes place and thecurrent to the driving motor is cut off. Thus, it is obvious that thetruck cannot be started directly on the higher speed, it being alwaysnecessary first to throw the lower speed into service.

Now, to determine the various connecting facilities for the contactdevice in the various positions of the operating rod, the inventionprovides for a cam l0 having a configuration adapted for the object inview. The cam forms part of a blocking contrivance adapted to fix thevarious positions of the operating member of the contact device. In theconstruction shown, the operating member of the contact device comprisesa handle it extending through the upper portion of the operating rod 8,said upper portion being formed as a hood !2 enclosing the contactdevice. The cam l O is rigidly arranged on or keyed to the pin or shaft9 fixed in the bearing housing 1 and having the operating rod 8pivotally mounted thereon. In addition to the cam 10, the blockingcontrivance comprises a blocking rod l3 arranged for cooperation withthe cam, said blocking rod being axially displaceable in the operatingrod 8 and formed at the top with or being adapted to be actuated by afork 14 having a shank l5, I6 on either side of a plane containing thegeometrical axis of rotation A for the operating member ll of thecontact device and the longitudinal axis of the operating rod, theoperating member or handle H being formed within the hood I2 with asupporting surface 11 extending at right angles or sub stantially so tosaid plane. The fork l4 may be substituted by a head Ma, Figs. and 10a,having a blocking surface Mb at the top opposite the supporting surfacell, which forms the bottom of a recess Ila. The opposite short edges ofthe blocking surface Mb correspond to the points of the shanks l5, H3.The supporting surface I! is intended to cooperate with the end portionsor points of the fork shanks l5, It or of the edges of the blockingsurface Mb. In the example shown in Fig. 3, the blocking rod is made intwo, preferably coaxial parts, that is to say an upper part [8 formedwith the fork l4 and a lower part 19, to the lower end of which issecured a guiding plunger 2| fitted into a bore 2D in the lower endportion 8 of the operating rod 8. Mounted in said guiding plunger is aroller 22 cooperating with the cam disk ID. The upper part 18 of theblocking rod is displaceably fitted into a bearing block 23 on theinside of the hood l2, and is actuated by a spring 24 'arrange in saidbearing block, said spring tendillg to move the fork l4 upwardly intoabutting contact with the supporting surface ll. Provided in a guide 25for the upper end of the lower portion IQ of the blocking rod is aspring 28 between an abutment 2i on said guide and a stop ring 28 on theportion 19, said spring tending to move the part l9 downwardly, so as tokeep the roller 22 bearing on the periphery of the cam i6. There maybe asmall play between the ends of the rod members l8, l9 fac ing eachother, said play permitting of being adjusted by means of an adjustingscrew 29 or the like threaded into the end of one of the rod members.

In the drawings (Fig. 3), the contact device is indicated only as takingthe form of a slidin contact 3Q bearing on the peripheral portion of theoperating handle I! within the hood l2, but as illustrated in Figs. 10and 10a there may be provided the number of sliding contacts 30a, 30b,30c and contact segments Ha, Ha, lib, llc arranged on the operatinghandle and other electrical contrivances required to impart differentspeeds to the driving motor, or adapted to engage and disengage thelatter in accordance with different angular positions of the operatinghandle. The contact springs 30a, 30b and 300 are each connected by alead 60 to a controller box 6| which contains relay switches for thecircuits of the electromotor and their connection with the storagebattery 6. Said switches and circuits are adapted to impart twodifferent speeds to the motor, one low speed and another high speed. Thecontroller 6! may comprise any conventional circuit, such as shown inFig. 9 of U. S. Patent No. 2,399,605.

In the starting position illustrated, wherein the supporting surface I!is at right angles to the longitudinal direction on the blocking rod,the contact device is taken to have cut oif the current to the drivingmotor. At the turnin of the handle I! from this position in a clockwisedirection, it is possible in dependence on the magnitude of the turningangle to throw the lower and then the higher driving speed into servicefor forward drive, and when the handle is turned from the startingposition in a counter-clockwise direction, it is possible in a similarway to throw the lower and then the higher speed into service forbackward drive, a indicated by the double arrow 3! in Fig. 3 and by thepointer 32 in Figs. 5-9. In Fig. 5, the position of the operating handleis indicated at the throwing of the lower speed into service forbackward drive corresponding to'engag'ement between contact 30a andcontact segment Ha, Fig. 10, and in Fig. 6 its position is indicatedrelative to the higher speed for backward drive corresponding toengagement between'contact 30b and segment I lb. In Fig. 7, its positionis indicated for the lower speed for forward drive (3011 and Ila beingengaged), and in Fi 8 the position is indicated for the higher speed forforward drive (300 and He being engaged). Fig. 9 indicates the 0position corresponding to theposition of the parts in Figs. 3 and 10. Inthe starting position shown in Fig. 3, however, the blocking rod and itsfork I4 prevent every turning movement of the handle H, inasmuch as theshanks of the fork are abutting against the supporting surface I! andthe rod member l8'is prevented by the rod member l9 from being displaceddownwardly, while the rod member I9 is kept in an upper position bymeans of-the cam l0, inasmuch as the roller 22 is here on a circularportion 33 of the periphery of the cam- I0. However, the cam is providedwith a depression 34 of such configuration that, when the rollercooperates with difierent'parts thereof, the blocking rod can bedisplaced downwardly, the fork [4 being consequently unable to preventthe handle II from being turned. Those sectors of the cam within whichthe latter cooperates with the roller 22 for theguidance of the blockingrod into and in different positions are denoted in Fig. 3 by 0, I, II,I, and ll, in the same manner as are the angular zones for the operatingrod 8 in Fig. 1. It should be noted here that the sector II, which has acurved outline concentric to the angular are 33, permits throwing of thelower as well as of the higher speed into service. When the operatingrod 8 is swung forwardly from the verticalposition shown, the roller 22rolls down into the depression 34, so that the rod member I!) is moved ythe sprin 26 fora distance downwardly Within the operating rod 8. Thehandle I I may then be turned, but no more than permitted by the forkHi. When the handle is turned in the one or the other direction, thesupporting surface ll presses the fork downwardly, until the lowerend ofthe fork rod l8 isstopped by the screw 29. As long as the roller 22 iswithin the sector I, it only permits small displacement of the blockingrod and a corresponding small turning movement of the handle H, but whenthe roller reaches the sector II upon a continued downward movement ofthe operating rod 8, it

has permitted a further displacement of the v blocking rod, a furtherturning movement of the handle H being thus permitted corresponding tothe lower and the higher driving speeds respectively.

The operating rod 8 is also intended to actuate the brake by means ofwhich the traction wheel 5 of the lift truck is braked. To this end,acam 40 is formed on the lower portion of the operating rod located inthe bear-inghousing ll, said cam being adapted to cooperate with aroller 4| mounted on the upper end of a double-armed lever 42. Thislever is mounted on a bolt '43 on the inside of the bearing housing 1,and the lower end thereof is pivotally connected to a brake arm 45 bymeans ofa pin 44. The brake 45 is provided with a wedge-shaped endportion 46 extending in between a pair of rollers mounted at the freeends of a pair of brake shoes 48, the

other ends of which are carried by fixed bearing pins 49. The brakeshoes are actuated by a spring 48' compressed by bolts 48""forcooperation with a'brake drum 58, which i secured on a counter-shaftbetween the motor 50' and the traction wheel 5. In the illustratedposition of the operating rod 8, the roller 4| is outside the one end ofthe cam 40, the wedge-shaped end portion 46 of the brake arm being thendisplaced inwardly so far as not to touch the rollers 41. This is alsothe case, when the operating rod takes a horizontal position. If theoperating rod '8 is moved forwardly from the vertical position orupwardly from the horizontal position, the cam 40 is brought intocontact with the roller 4|, so that the'lever 42 is swung in a clockwisedirection about the bearing bolt 43, the brake arm 45 being thus pulledto the left in Fig. 3, whilethe Wedge-shapedend portion 46 thereofforces the rollers 41 apart so as to raise the brake shoes 48 from thebrake drum 50, so that the brake is disengaged. As soon as the operatinrod is moved from a driving position into the vertical or horizontalposition, the brake is rendered operative.

- The arrangement described is distinguished not only by a simpleconstruction, but also offers particular advantages in regard toreliable operation and simple manoeuvring, whereby manoeuvring faultsare excluded as far as possible. For example, it is not possible tostart the lift truck 'on the higher speed, it being always necessaryfirst to switch in the lower speed. It should be noted, furthermore,that the operating handle ll of the contact device is automaticallyturned back into the starting position, if the operating rod 8 isswungback to the nearest extreme position from zone 11 or any of thezones I and I. This is so for the reason that the roller 22 will then bemoved up toward the circular portion 33 of the cam disk to force theblocking rod with the fork [4 to exert a pressure on the supportingsurface ll on the one or the other side of the turning center of thehandle ll, so that a turnin moment is produced, which turns the handleback. The motor will thus always be stopped and the truck braked, whenthe operating rod is swung toward the extreme positions, whether thehandle H is turned by the driver or not. Confusion between a higher anda lower speed is also excluded, when the lift truck is standing still.

What we claim is:

1. A control mechanism for electrically motor driven lift trucks,comprising an operating rod pivoted to be swingable to differentintermediate positions between extreme positions within a certain angle,an adjustable operating handle mounted on the operating rod, a contactdevice operated by said handle to control the driving motor, and ablocking contrivance including a cam member for cooperation with saidoperating rod and handle to determine definite contact positions of saidhandle in dependence upon the angular positions of the operating rodrelatively to the cam member and to prevent the handle to beset in othercontact positions, said cam member and operating rod being relativelyrotatable.

2. A control mechanism as claimed in claim 1, wherein said blockingcontrivance is adapted to determine two extreme positions of theoperating handle for every intermediate position of the operating rod,one of said extreme handle positions being a position for forward driveand the other a position for backward drive.

3. Acontrol mechanism for motor driven lift 'trucks, comprising ahousing, a shaft keyed to.

the housing, a cam, keyed to said shaft, an-operating lever journalledon the shaft and pivoted to the housing to be swingable to variouspositions within a certain angle, an operating member mounted rotatablyon said operating lever for adjustment to various operating positionscorresponding to various motor speeds and driving directions, saidmember having a supporting surface, a blocking rod having one endportion formed with a blocking surface for cooperation with saidsupporting surface, said supporting surface having edges at oppositesides of a plane including the axis of rotation of the operating member,the other end portion being adapted to cooperate with the cam, theblocking rod being slidably mounted in the operating lever to takedifferent positions relatively to said supporting surface as theoperation lever is set to different angular positions relatively to thecam and the blocking rod engages different points of the cam.

4. A control mechanism as claimed. in claim 3, wherein the blocking rodcomprises a roller for cooperation with the cam.

'5. A control mechanism as claimed in claim 3,

wherein the blocking rod comprises two coaxial spring and a memberadapted to be moved by i said second mentioned spring in a direction toward the curved surface of the cam disk, the play between the ends ofsaid rod members facing each other being adjustable by means of a screwor the like threaded into one ofthe rod ends.

6. In lift trucks having a carrying wheel driven by an electric drivingmeans for low speed drive and high speed drive, a control mechanismcomprising an operating lever pivoted to be swingaole to variousintermediate positions between .extreme positions, an adjustableoperating member mounted on the operating lever, a contact deviceoperated by said operating member to control the driving means, ablocking contrivance including an independent cam adapted to cooperatewith said lever for determining definite contact positions for saidcontact device as switched-out positions corresponding to the extremepositions of the lever and a number of switched-in positionscorresponding to the inter-' mediate positions f the lever, said cam andoperating member being relatively rotatable, and the blockingcontrivance being devised to permit switching-in of only a low speedwithin zones of intermediate positions adjacent the extreme positions ofthe lever and to permit switchingm of low as well as high speeds withina zone of intermediate positions between said low, speed zones,

7. In lift trucks having a carrying wheel driven by an electric drivingmeans, a control mechanism comprising a housing and a shaft keyed to thehousing, a cam keyed to the shaft, an operating lever pivoted to theshaft, a contact device for the operation of said driving means, ahandle mounted adjustably on the operating lever, means in said levercooperating with said cam to determine definite positions for saidhandle and contact device in dependence upon the position of the leverrelatively to the cam, said cam and operating lever being relativelyrotatable, a further cam secured to the lever, a brake for the drivlngmeans and means transmitting movement from said lever cam to the brakefor disengaging and engaging the brake, the lever cam being angularlydisposed relative to the cam keyed to the pin or shaft whereby theengagement and disengagement of the brake is dependent on the angularposition of the operating ever.

8. A control mechanism as claimed in claim 3,

wherein the edges of the blocking surface are formed by the points of afork at the end of the blocking rod. 9. A control mechanism as claimedin claim 6, in which the lever includes a cam on thelower end of thelever and as a part thereof and in which brake means are providedadapted to be operated by the lever through said lever cam.

Name Date Schroeder Apr. 30, 1946 Number

